Post harvest diseases fruits and vegetables - Xavier University ...

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
120 Postharvest Diseases of Fruits and Vegetables
found that intermittent warming treatments in grapefruit made it
possible to reduce the recommended dosage of the fungicide benomyl by
50%, from 600 to 300 ppm, while still maintaining good decay control.
The advantage of intermittent warming in enhancing fruit resistance to
chilling injury has been proven for Olinda oranges: 2 weeks of
intermittent warming to 15°C every 3 weeks, during storage at 3°C,
delayed the onset of chilling injury by 15 weeks and greatly suppressed
the incidence of damage during the subsequent 10 weeks of storage
(Schirra and Cohen, 1999). Experiments with lemons have shown that
intermediate heating to 13°C for 7 days after every 21 days enables them
to be stored at 2°C, a temperature much lower than the optimal storage
temperature for the fruit. Under these conditions, the percentage of peel
pitting, characteristic of lemon fruits stored at 2°C, was markedly
reduced and decay was suppressed (Artes et al., 1993; Cohen et al.,
1983). The technique of storing lemons at 2*^C with intermittent warming
at 13°C has been adopted as a commercial method for long-term storage
of these fruits (Cohen, 1988).
Mature-green tomato fruits are susceptible to chilling injury at storage
temperatures below 12®C. Chilling injury symptoms include surface
pitting, uneven ripening or failure to ripen, and altered flavor. These
symptoms are accompanied by increased disease development (Hobson,
1981; Cheng and Shewfelt, 1988). Intermittent warming treatments have
proved to be effective in reducing chilling injury in tomatoes, to an extent
which depends on the cultivar and the time-temperature regime. Artes
and Escriche (1994) found that storing the fruit at 9°C (but not at 6°C),
with cycles of intermittent warming at 20°C for 1 day every 6 days, was
effective in reducing chilling injury symptoms in two tomato cultivars,
while fruits stored at a continuous 9°C were susceptible to Alternaria
decay, which typically developed on the pitted area. Intermittent
warming was more beneficial than intermittent cooling; pitting
developed at 2°C in the intermittently cooled fruits (Artes et al., 1998).
Chilling injury is not limited to fruits of tropical or subtropical origin.
Cultivars of peaches, which were recommended for storage under
refrigerated conditions, may develop chilling injury symptoms, including
breakdown or woolly breakdown, discoloration, low juice content, and
failure to ripen or to ripen normally. Intermittent warming at 20°C or at
higher temperatures, for 1-3 days every 2 weeks, during storage at 0 or
1°C, gave good control of chilling injury in peaches (Ben-Arie et al., 1970;
Buescher and Furmanski, 1978); while intermittent warming at 18^C for
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